Check that little groove that holds ramcap in its place. Ball bearing may have hammered little burr in the end of it.

You should cut or grind off this little burr and check that ball bearing is tightened correctly. there should be quite snug fit, when you replace or remove your ramcap. Be careful tho. It's easy to overtighten the ball bearing and ruin your ramcap. Tighten just a bit and test. Repeat this until it's hard to twist the cap.

When your cap fits snugly in it's place, it wont hammer it's groove and ramcap wont fall off during gameplay.

Grab the thin end of the ram and wiggle it out. The ball bearing does flare its channel a bit (you may not even notice it) and once you get the ram out it smooths back down. Then it should go in/out easily.